Control method for controlling slag remaining amount of converter

Abstract

The invention relates to the technical field of converter slag remaining amount, in particular to a control method for controlling the converter slag remaining amount, which comprises the following steps: step 1, slag adjustment: adjusting slag to a relatively fixed slag specific gravity; step 2, slag remaining: setting a maximum slag pouring angle according to the furnace profile and the furnace service, so that the volume of the slag retained in the furnace is fixed; and 3, adjusting the set angle value according to the slag splashing time, so that the slag splashing time meets the requirement. Accurate control over the slag remaining amount is achieved, and the slag splashing furnace protection effect is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of slag retention amount in converters, and specifically refers to a control method for controlling the slag retention amount in converters. Background Art

[0002] There are currently two methods for the slag splashing and furnace lining protection process in converters. One is to splash slag first and then pour out the remaining molten slag; the other is to pour out the slag first and then splash slag. Usually, both slag splashing modes take the absence of slag splashing at the furnace mouth as the end point. Therefore, the former has a longer slag splashing time and a larger consumption of medium-pressure nitrogen for slag splashing. As a result, many steel mills adopt the mode of pouring out the slag first and then splashing slag. However, it is difficult to control the amount of retained slag, which often leads to too short a slag splashing time, thus affecting the effect of slag splashing and furnace lining protection.

[0003] For the latter, how to accurately control the amount of retained slag, flexibly adjust the slag splashing time without affecting the slag splashing effect, and save the consumption of medium-pressure nitrogen for slag splashing has become a problem to be solved in this field. Summary of the Invention

[0004] (1) Technical Problem

[0005] The present invention aims to solve at least the problem of how to accurately control the amount of retained slag in the mode of pouring out the slag first and then splashing slag existing in the prior art.

[0006] (2) Technical Content

[0007] This solution provides a control method for controlling the slag retention amount in a converter, including the following steps:

[0008] Step 1: Adjust the slag. Adjust the slag to a relatively fixed slag specific gravity.

[0009] During the tilting process of the converter and when tapping the steel, the steelmaker checks the consistency of the molten slag. If the molten slag is too thin, it needs to be adjusted to a thicker slag.

[0010] Step 2: Retain slag. Set the maximum tilting angle for pouring out the slag according to the furnace type and furnace campaign to make the volume of the retained slag in the furnace fixed.

[0011] Set a fixed pouring-out angle. When pouring out the slag after tapping the steel, each time pour out the slag at the same tilting speed of the converter, tilt the converter to the set pouring-out angle, stay for the same time, or stop pouring out the slag until the molten slag in the furnace no longer flows out.

[0012] Step 3: Adjust the set angle value according to the slag splashing time to make the slag splashing time meet the requirements and ensure the slag splashing and furnace lining protection effect. Control the amount of retained slag according to the set pouring-out angle and conduct tracking. If the slag splashing time is too long, the tilting angle of the furnace can be appropriately increased to reduce the amount of retained slag;

[0013] If the slag splashing time is too short, the pouring-out angle can be reduced to increase the amount of retained slag.

[0014] Preferred Technical Solution 1: In Step 1, during the tilting process of the converter, if the steel slag is too thin, the first thickening is carried out, specifically:

[0015] Add materials such as lime and lightly burned magnesia balls into the converter furnace through the high-level bunker to thicken the slag.

[0016] Preferred Technical Solution 2: In Step 1, after the first thickening, if the slag is still too thin during tapping, the second thickening is carried out, specifically:

[0017] Thicken the slag by manually adding modifiers, coke powder and other materials.

[0018] Preferred Technical Solution 3: In Step 2, the slag pouring angle is 95 - 105°.

[0019] (III) Technical Effects

[0020] Adopting the above structure enables this solution to have the following beneficial effects:

[0021] 1. In the original slag retention method, the steel slag has different consistencies, and the volume of the retained slag is not fixed, making the retained slag volume extremely unstable. It is easy to have problems such as too little retained slag, short slag splashing time, poor furnace lining protection effect, and too much retained slag, long slag splashing time, waste of medium-pressure nitrogen for slag splashing, and affecting the production rhythm.

[0022] 2. By adjusting the consistency of the steel slag and fixing the slag pouring angle, the proportion and volume of the steel slag retained in each furnace can be kept relatively constant, thereby achieving precise control of the retained slag volume in the furnace and relative stability of the slag splashing time.

[0023] 3. It can not only ensure the effect of slag splashing for furnace lining protection, but also save the energy medium cost such as medium-pressure nitrogen used for slag splashing. At the same time, the slag splashing time can be flexibly adjusted by slightly adjusting the set slag pouring angle. Specific Embodiment

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0025] A control method for controlling the retained slag volume of a converter includes the following steps:

[0026] Step 1, adjust the slag to a relatively fixed slag proportion

[0027] During the tilting process of the converter and during tapping, the steelmaker checks the consistency of the steel slag (which can be judged by the steelmaker's experience). If the steel slag is too thin, it needs to be adjusted to thicken the slag;

[0028] During the tilting process of the converter, if the steel slag is too thin, the first thickening is carried out. Specifically, materials such as lime and lightly burned magnesia balls are added into the converter furnace through the high-level bunker to thicken the slag.

[0029] After the first thickening, when the slag is still too thin during tapping, the second thickening is carried out. Specifically, the slag is thickened by manually adding modifiers, coke powder and other materials.

[0030] Step 2: Retain slag. Set the maximum tilting angle for slag pouring according to the furnace type and campaign to keep the volume of the retained slag in the furnace fixed.

[0031] The converter furnace type is a relatively fixed geometric container. Theoretically, when the furnace is tilted to pour slag at the same angle, the volume of the remaining slag in the furnace is also the same.

[0032] Set a fixed slag pouring angle. When pouring slag after tapping is completed, tilt the converter to the set slag pouring angle at the same tilting speed each time (a buffer stop point can also be set in the middle to prevent production accidents caused by excessive slag pouring). Stay for the same time (such as 5 seconds), or stop pouring slag until the steel slag in the furnace no longer flows out.

[0033] The slag pouring angle is between 95 - 105°. Specifically, it can be adjusted according to different converter furnace types and campaign states. In the later campaign, the furnace lining is eroded more, the space in the furnace is larger, and the slag pouring angle can be controlled at the upper limit. In the early campaign, the furnace lining is eroded less, the space in the furnace is smaller, and the slag pouring angle is controlled at the lower limit.

[0034] Step 3: Adjust the set angle value according to the slag splashing time to make the slag splashing time meet the requirements and ensure the slag splashing and furnace lining protection effect. Track the retained slag amount according to the set slag pouring angle. If the slag splashing time is too long, the tilting angle of the furnace can be appropriately increased to reduce the retained slag amount.

[0035] If the slag splashing time is too short, the slag pouring angle can be reduced to increase the retained slag amount.

[0036] Example

[0037] For a 100t converter in a certain factory, when tapping each heat of steel, the steelmaker is required to adjust the slag according to the thickness of the steel slag. When the final oxygen content > 800ppm, 30 - 50kg of coke powder is required to be manually added for each heat of steel tapping; for the rest, an aluminum slag - type modifier is used to adjust the slag. Under normal furnace lining erosion conditions, during slag pouring, the furnace is tilted to 104° each time until no slag comes out of the furnace mouth, and then the furnace is lifted. At this time, the retained slag amount is controlled at about 3 ± 0.5 tons, and slag splashing starts. The average slag splashing time is about 117 seconds, and the nitrogen consumption for slag splashing is about 1100 Nm³. The furnace lining protection effect is good.

[0038] When the proportion of low-carbon steel smelting furnaces exceeds 50% and the overall oxidability of the molten steel is relatively strong, the slag pouring angle is reduced to 102°, and the slag retention amount is about 4 ± 0.5 tons at this time. The slag splashing time is extended to about 180 seconds, and the nitrogen consumption for slag splashing correspondingly increases to about 1440 Nm3, enhancing the slag splashing intensity and improving the ladle lining protection effect;

[0039] The remaining slag amount is controlled at about 3 ± 0.5 tons.

[0040] It should be noted that in this text, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device.

[0041] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the amount of slag left in a converter, characterized in that: The steps include: Step 1: Adjust the slag to a relatively fixed slag specific gravity. During the converter pouring process and steel tapping, check the consistency of the slag. If the slag is too thin, it is necessary to adjust the thick slag. Step 2: Retain slag. Set the maximum slag pouring angle according to the furnace type and furnace service to keep the slag volume in the furnace fixed. Set a fixed slag pouring angle. When the slag is poured out after steel tapping, the converter is tilted to the set slag pouring angle at the same tilting speed each time, and stays there for the same time, or stops pouring slag when the slag in the furnace stops flowing out. Step three, adjust the set angle value according to the slag splashing time so that the overall slag splashing time meets the production requirements and can ensure the slag splashing furnace protection effect.

2. A method for controlling the amount of slag remaining in a converter according to claim 1, characterized in that: In step 1, if the slag is too thin during the converter pouring process, the first thickening is performed.

3. A method for controlling the amount of slag remaining in a converter according to claim 2, characterized in that: In step 1, after the first thickening, the slag is still too thin when tapping the steel, so a second thickening is performed.

4. The method for controlling the amount of slag remaining in a converter according to claim 2, characterized in that: The first thickening operation is to add lime and light-burned magnesium ball thick slag into the converter furnace through the high-level silo.

5. The method for controlling the amount of slag remaining in a converter according to claim 3, characterized in that: The second thickening operation is to add a modifier and coke powder to thicken the slag.

6. The method for controlling the amount of slag remaining in a converter according to claim 1, characterized in that: In step 2, the slag pouring angle is 95-105°.